IMAGE PICKUP APPARATUS, CONTROL METHOD THEREFOR, AND COMPUTER PROGRAM FOR DETECTING IMAGE BLUR ACCORDING TO MOVEMENT SPEED AND CHANGE IN SIZE OF FACE AREA

An image pickup apparatus includes: a face detection section configured to detect a face area from an image obtained by the image pickup apparatus; and a control section configured to detect at least any one of the amount of change in size of the face area detected by the face detection section and a movement speed of the face area, determine whether there is a possibility of occurrence of subject shake blur, which is blur occurring in a captured image due to the movement of a subject, on the basis of information on the detected amount of change in size of the face area or the detected movement speed of the face area, and output a warning when it is determined that there is a possibility of occurrence of subject shake blur.